1. Field of the Invention
The invention relates to a bandwidth extension device comprising an input for receiving an input signal, filter means for filtering the input signal, creating means for creating an adapted signal with a lower frequency part than the input signal.
The invention further relates to an audio reproduction system comprising such a bandwidth extension device.
2. Description of the Related Art
Such a device is known from European Patent Application No. EP-A-0240286, corresponding to U.S. Pat. No. 4,790,014. To improve the aural sensation in low-pitched (that is: signals in the very low frequency band) sound reproduction by an audio reproduction system or the like, a sub-harmonics generator is used to create this low-pitched signal. In this way, a lower pitch signal is created than is present in the incoming signal.
A disadvantage of the known sub-harmonics generator and the known bandwidth extension device is that the amplitude of the sub-harmonics generator is not linear with the input voltage. Known sub-harmonics generators usually clip the input signal and then divide the signal by two, for example, with a flip-flop, also, for example, a phase-locked loop is used to obtain the sub-harmonics.